Here is an overview of my DIY solar charging system.
There are no one-size-fits-all RV solar solutions out there. If you are considering adding solar power to your RV, I recommend you learn as much as possible up front. I've found the most effective way to learn is to analyze what others have done. So let me tell you about the solar charging system on my RV and maybe it will help you piece together a system that works for you.
Our RV Off-Grid Power System In a Nutshell
We have roughly 500 watts of solar panels connected to multiple Victron MPPT solar charge controllers which keep our 450 amp hours of AGM deep cycle batteries charged. Our 2000 watt pure sine inverter converts 12 volt DC power from the batteries to 120 volt AC household power used throughout the entire RV. To keep track of our power usage and available power, we use a battery monitoring system from TriMetric.
The diagrams in this article show lots of minor components that make the whole thing work, but the equipment I mentioned are the major ones.
With this setup, we can travel and live completely off-the-grid in our RV. We can even use our microwave, hair dryer, and Keurig coffee maker without having to plug in or run a generator.
All equipment, cabling and tools I used were purchased through Amazon. Please consider using the links through our parts list (below) to shop for these items. There's no additional cost and you'll be helping to support us if you do.
Here is our full solar equipment list
RV Solar Panels
I have two types of flexible solar panels installed on the roof of my RV, Unisolar thin-film solar panels and HQST semi-flexible monocrystalline solar panels. I separated each panel type into two arrays because the panel specifications vary quite a bit.
The Unisolar flexible solar panels were installed in 2012. At that time they were the only flexible solar panels available. There are two 64 watt panels and one 128 watt panel. The two smaller panels are connected in series and those are connected in parallel with the 128 watt panel.
The Unisolar panels are still going strong despite the fact that the company went bankrupt many years ago. It’s too bad. They had a great product. I decided not to replace them because, get this, they still out perform the newer HQST monocrystalline semi-flexible solar panels I have installed.
The second array includes three 100 watt HQST semi-flexible solar panels wired in series. Several years ago, Renogy was having issues with these panels. So they sold the production rights for these panels to HQST. HQST fixed the problems and continue to crank out these panels. I picked up the HQST solar panels fom Amazon and installed them in 2016.
Semi-flexible solar panels are still pretty new to the market, so nobody really knows how long they will last. So far they have been working fine and I haven’t had to replace any.
Junction Box to Simplify Solar Panel Wiring
I created a junction box on my RV roof to hide and protect all of my solar panel connections. All of the solar panels are wired directly to this junction box.
Unlike a typical solar combiner box used to connect solar panels in parallel, these terminal blocks also allow me to connect panels in series and split my panels into two separate solar arrays. I can also change my configuration in the future without having to move or run new cables.
I eliminated all of the cable "T" connectors and MC3 to MC4 adapters after installing the junction box (see video below). All all connections are now made inside the box.
Here’s a video to show how I built and wired the Solar Junction Box.
Parallel MPPT Solar Charging
Each solar array on the roof (the Unisolar array and HQST array) is connected to its own dedicated Victron 100/30 MPPT solar charge controller. A third Victron 75/15 MPPT charge controller is installed to accommodate a portable solar panel.
All three solar charge controllers are wired in parallel and share the same charge profile for charging my AGM battery bank.
Here’s a video explaining how and why I installed my MPPT solar charge controllers in parallel to charge my battery bank.
All energy in and out of the battery flows through a device called a shunt. The energy measured across the shunt is reported to my TriMetric Battery Monitoring System.
Without a battery monitoring system, I would have no idea how much power I am using in the RV or how much battery capacity is available. There are also good BMS devices available from Xantrex and Victron. Every off-grid system should include a battery monitoring system (with or without solar). It should be the first thing you install. I recommend going with a Victron BMS if you have Victron charge controllers. Likewise, if you have a Xantrex inverter, you may want to go with a Xantrex BMS.
AC Power from Your Batteries
My Samlex 2000 watt pure-sine inverter converts 12 volt DC power to 120 volt AC power. The AC power from the inverter simulates a shore power connection and powers all of the household AC receptacles in the RV.
Installing a power inverter can really make your RV feel like you are hooked up at an RV park. I can run just about everything except my electric heaters and A/C unit. Backed by my 450 amp hours of AGM batteries, we can run the microwave, use our Keurig to make coffee from the inverter.
The game changer was when my wife was able to use her blow dryer on the inverter. Yes. I was a hero after that.
Important: Disconnect Converter/Charger While Using The Inverter
With my converter/charger indirectly powered through my inverter, there was a potential problem. Without disconnecting the converter, my batteries would try to charge themselves through the inverter. Not good.
My RV has a circuit breaker on the converter/charger power connection, so I made sure to shut-off the converter/charger manually each time we switched on the inverter. Eventually I would install an automatic shutoff device (see video below).
Keep in mind that this is not an issue in some larger RVs with a combination inverter/charger/transfer switch unit.
Confused? Here's a video that explains it all.
I later installed an automatic shutoff switch which gets triggered when the inverter powers up. Now it's a no-brainer and is very much appreciated by my wife who just has to turn on the inverter for AC power. No more messing with the power panel.
Well that's an overview of the off-grid power system in our RV. Much of the detail is in the diagrams. So if you have questions please leave a comment and I'll provide an explanation. I hope this helps you out!